The automated assembly or processing of components is conventionally performed during continuous motion on a rotating platform or dial having multiple identical tools. Optionally robotic assembly or processing can occur in a “pick and place” system which can work with stationary or moving component parts and stationary or moving tools. The continuously moving tools on a continuous motion dial receive one or more components from one or more delivery devices along the rotary path of the tools on the dial. A single component is processed (such as folding, shaping, punching or turning processes), or multiple components are assembled together and ejected from the tools when the operations are completed. Typically tools are controlled with peripheral cam surfaces and the tool has a follower wheel that engages the cam surface to operate the tool through the repeating cycle that occurs on each revolution of the dial.
Since the tools are continuously rotating on the dial, the delivery devices must take a lead component from a stream of like components at a stationary or moving start position and accelerate the component to a speed that matches the tangential speed of the dial as the tool passes and the component is handed off from the delivery device to the tool on the rotating dial.
Output in finished pieces/minute can be expressed as follows:Output=(1 piece/tool)×(number of tools/dial revolution)×(dial revolutions/minute)=number of pieces/minute.
In order to increase the output of processed or assembled finished pieces from a conventional continuous motion system, the number of multiple tools on a dial can be increased. Increasing the dial speed (dial revolutions/minute above) can also increase output. However when the dial speed increases, the speed at which components are handed over to the dial must increase as well. The dial speed has been found to be a limiting factor in increasing output due to the practical maximum speed at which conventional component delivery devices can operate reliably. As a result the conventional preference is to increase the number of tools on a dial to increase output. However individual tools are expensive to build and maintain, and multiplying the number of tools increases the costs and likelihood of equipment failure. Increasing the number of tools may also increase the diameter of the dial, resulting in a larger machine occupying greater floor space. Downtime increases as tool numbers increase since the operation of the entire dial must be stopped if one tool malfunctions. Converting multiple tools to process or assemble new components also multiplies the costs of operating a conventional continuous motion system.
Therefore to reduce costs, a reduction in the number of tools is desirable. However to increase production the conventional approach has been to increase the number of tools per dial since a limiting factor has been the speed of dial rotation and matching speed at which components can be delivered and handed off to the continuously moving dial without errors or damaging components in the process.
Feed screws have been used to separate a lead component from an adjacent component, accelerate components to the tangential speed of the continuously moving dial and tools and match component delivery to the pitch or spacing between adjacent tools on the dial. As spacing between tools on the dial increases, the screw pitch must be increased equally. The screw pitch must match the circumferential spacing between tools on the dial so that component delivery is timed to coincide with the arrival of the tools at the position where the component is handed off to the tool from the screw. As spacing between tools on the dial is increased, and the screw pitch is increased the component engagement angle of contact between the component and the helical groove of the screw becomes more acute resulting in less axially directed force and more radially directed force. Components may be damaged or jammed as a result of the combination of radial and axial forces exerted on the components by the conventional feed screw and guides at high speeds. To increase output, the speed of rotating the dial or the number of tools on the dial must be increased. In either case the rate of delivery of components by the feed screw must also be increased to ensure component delivery coincides with arrival of multiple tools in succession at the component hand off position. However using conventional continuous motion methods, it has not been possible to increase output without also requiring multiple tools positioned on a dial.
Continuous motion assembly and processing has been limited to certain types of components and to maximum practical speeds due to limitations in the delivery of components using conventional processes and equipment. As a consequence typical dials hold 10 to 50 identical tools that are cam operated or operated by fluid power. The adoption of electronic controls and servo drive motors for actuation has been impeded by the costs involved in use of multiple tools and the practical limits in handing off components at high speed using conventional feed screws. Programmable robots have been used for complex operations and provide a high level of flexibility in adapting to varying operations through programmed motion control, however at a very high cost for high volume repetitive processes.
Features that distinguish the present invention from the background art will be apparent from review of the disclosure, drawings and description of the invention presented below.